This was a multi-center, open-label dose escalation Phase I trial designed to test the safety, pharmacokinetics and preliminary biologic activity of BMS-188667 (CTLA4Ig) administered as four intravenous injections on days 1, 3, 16, and 29 to patients with psoriasis vulgaris. The major goals of this study were the determination of: the safety, pharmacokinetics, immunogenicity, recovery time from biological effect and optimal diologic dose for psoriasis treatment of BMS-188667.